Variable resistance installation characterized by sine-functional resistance variation



June 1966 TADASHI HIROTA ETAL 3,

VARIABLE RESISTANCE INSTALLATION CHARACTERIZED BY SINE-FUNCTIONAL RESISTANCE VARIATION Filed Aug. 21, 1963 INVENTORS 'TAoAsm Hmvrflfimceml mam momumzu Sumo ml scowra, TQME'DMMATBHM mmmo ATTORNEYS.

United States Patent 3,257,633 VARIABLE RESISTANCE INSTALLATION CHAR- ACTERIZED BY SINEr-FUNCTIONAL RESIST- AN CE VARIATION Tadashi Hirota, Shigemi Hirota, and Nobukazu Sulro, Tokyo, Japan, assignors to Taiyosha Inc., Uta-kn, Tokyo, Japan, a corporation of Japan Filed Aug. 21, 1963, Ser. No. 303,577 5 Claims. (Cl. 338-91) This invention relates generally to a variable resistor and more particularly to a variable resistor wherein the value of resistanc varies sinusoidally.

In order to maintain a minimum degree of error in variable resistors which vary according to the equation:

R=(A) sin 0 where: R is the total resistance in ohms; A is the maximum resistance in ohms; and 0 is the angle through which the input shaft rotates,

the resistance elements are usually produced with a high degree of accuracy. Moreover, these elements must be capable of withstanding abrasion due to the continuous movement of the wiper as it slides across the resistor. Additionally, special production techniques are required in the manufacture of the above-mentioned device since unique properties must be imparted to the resistance elements to have the total resistance vary sinusoidally. The observance of these requirements in the production of a device of the type described materially increases the cost thereof.

It is an object of the present invention to produce a variable resistor whose value varies in accordance with a sine-function which is relatively economical and highly accurate.

It is another object of the present invention to produce a variabl resistor whose value varies in accordance with a sine-function which utilizes linear resistance elements.

In accordance with the present invention, an embodiment thereof comprises a driving gear rotatably mounted to a shaft and in meshing engagement with stationary gear. The shaft is connected, by an arm, to an input shaft whose axis is concentric to the axis of the stationary gear.

The gear ratio of the stationary gear to the driving gear is 2: 1. A brush is mounted to the driving gear and overlies a point on its pitch circle. A pair of resistance elements are mounted parallel to a diameter of the stationary gear which passes through the hereinbefore mentioned point and are in slidable contact with the brush. Rotation of the input shaft will cause the brush to describe a sinusoidal variation with respect to the axis of the driving gear andreciprocating motion with respect to the said diameter. Hence, the total value of resistance appearing between the resistance elements will be proportional to the sine of the angle that the input shaft rotates through.

It is a feature of the present invention to provide a device which converts mechanical motion into a sinusoidal resistance variation.

The above and other objects and features of the present invention will become more apparent from a consideration of the following description when taken in conjunction with the drawings in which:

FIG. 1 is a perspective view of a device which produces an output resistance which varies as the sin of the angle the input shaft rotates through, in accordance with a first embodiment of the present invention; and

FIG. 2 is a perspective view of a second embodiment of the present invention with the internal ring gear of FIG. 1 replaced by a gear train.

It is to be understood that like numbers in the various figures indicate identical elements.

3,257,533 Patented June 21, 1966 FIG. 1 illustrates a first embodiment of the present invention utilizing -a planetary gearing arrangement. An input shaft is connected to an input source of power (not shown). An arm 12 is fixedly connected to shaft 10 and to a shaft 14, which is parallel to shaft 10. Rotatably mounted on shaft 14 is a driving gear 16 which meshes with a stationary internal ring gear 18. The axis of shaft 10 is concentric with the axis of internal ring gear 18. Moreover, th ratio of the number of teeth 19, on gear 18, to the number of teeth 17, on gear 16, is 2: 1. That is, if there are n teeth on gear 16 there will be 211 teeth on gear 18.

A block 20, having an undercut surface 21, is movably mounted on gear 16 in any conventional manner. Thus, gear 16 may have a slot (not shown) therein to receive a threaded shaft (not shown) integral with the bottom portion of block 20. A nut maybe screwed onto this threaded shaft to abut the lower side of gear 16 thereby securing block 20 in place. An aperture is formed in the top portion of block 20 and receives a shaft 22 therein, the axis of shaft 22 being parallel to the axis of shaft 14. Block 29 is then adjusted until the projection of the axis of shaft 22 through block 20 overlies a point on the periphery of the pitch circle of gear 16.

An elongated brush 24, composed of a conducting material, is connected to the end of shaft 22 in any conventional manner, with the axis of brush 24 concentric to the axis of shaft 22. Thus, the end of shaft 22 may be threaded to be received in a threaded aperture in the bottom of brush 24. A pair of linear rod-like resistance elements 25 and 26, having longitudinal axis 25a and 26a, respectively, are mounted by insulators (not shown) so that the axes 25a and 26a lie in planes which are parallel to the plane of a diameter of internal ring gear 18 which passes through the point on the pitch circl of gear 16 that shaft 22 overlies. Moreover, elements 25 and 26 are positioned so that brush 24 is in sliding engagement with them. Element 26 is connected to a terminal 28 by a lead 29. Element 25 is connected to a terminal 30 by a lead 31. Thus, the variable resistor of the present invention may be connected to an electrical circuit by connecting the respective terminals 28 and 30 to the desired points in the circuit.

In operation, shaft 10 is caused to rotate thereby moving shaft 14 through the connection of arm 12. This will cause gear 16 to rotate on shaft 14 because the teeth 17 will mesh with the teeth 19. In accordance with the well-known theory of kinematics, shaft 14 will generate a sine-wave, as a function of time, with respect to a fixed diameter of shaft 10. Moreover, the aforementioned point on the pitch circle of gear 16 will likewise generate a sine-wave with respect to a fixed diameter of gear 16. However, since the gear ratio is 2:1 and the axis of shaft 10 is concentric with the axis of gear 18, then the point on the pitch circle of gear 16 will execute a reciprocatory motion along a diameter of gear 18 passing through the point. Thus, brush 24 will slide back and forth between elements 25 and 26 as a sinusoidal function of the angle through which input shaft 10 rotates.

Hence, the total resistance appearing between terminals 28 and 30 will therefore be dependent upon the sign of this angle.

In accordance with the present invention I have provided a device which varies the resistance of an element according to a sine-function in accordance with the relationship given by the equation:

' R: (A) sin 0 FIG. 2 illustrates a second embodiment of the present invention with the internal ring gear 18 of FIG. 1 replaced by a conventional spur gear. Thus a shaft is fixedly connected to an arm 112 and rotatably passes 3 through a gear 118. The axis of shaft 110 is concentric with the axis of gear 118. Arm 112 has an aperture 40 at the end thereof and a shaft 14 fixedly connected at a point intermediate the connection to shaft 110 and aperture 40. A shaft 41 is rotatably mounted within aperture 40 and has a gear 42 aflixed to one end thereof and a gear 43 affixed to the other end thereof. Gear 42 meshes with gear 118 and gear 43 meshes with gear 16, which is rotatably mounted on shaft 14. The other elements in this embodiment are the same as those elements described above and operate in the samemanner. The number of teeth on gear 42 and gear 43 are equal while there are twice as many teeth on gear 118 as there are on gear 16.

In operation, gear 18 is stationary and is maintained in place by any conventional means (not shown). A rotation'of shaft 110 causes arm 112 to move; hence, gear 42 will mesh with gear 118 thereby turning gear 43 through the coupling of shaft 41. Gear 43 will, in turn, cause gear 16 to rotate about shaft 14 while shaft 14 describes a circle about the axis of 110. Hence, it is obvious that the principle of operation of this device is the same as the device illustrated in FIG. 1. That is, conductor 24 will reciprocate back and forth with respect to a diameter of gear 118 passing through the plane of the point on the pitch circle of gear 16, and in sliding engagement with elements 25 and 26. Thus, the total resistance appearing between terminals and 28 will vary according to the sine of the angle which shaft 110 rotates through. Accordingly, the resistance of the device illustrated in FIG. 2 will likewise be determined by the equation: v

R: (A) sin 9 Having described preferred embodiments of the present invention, it will be apparent to those skilled in the art that modifications may be made therein without departing from the scope of the invention. Therefore, we do not wish to be limited by the arrangements disclosed, but only by the claims annexed hereto.

What is claimed is:

1. A device of the type described comprising an input shaft, an arm fixedly mounted to said shaft, a second shaft fixedly mounted to said arm outwardly of said input shaft and having an axis parallel to the axis of the input shaft whereby rotation of said input shaft will cause said second shaft to move in a circle about the axis of said input shaft, a first stationary gear being so positioned that its axis is concentric to the axis of said input shaft, a second gear rotatably mounted on said second shaft and in driving connection with said first gear, the gear ratio of said first gear to said second gear being 2:1, a brush, means for mounting said brush to said second gear and for positioning said brush so that it overlies a particular point on the pitch circle of said second gear and the axis of said brush is parallel to the axis of said second shaft, a pair of linear [resistance elements abutting said brush and in slidable engagement therewith, each of said resistance elements having a longitudinal axis, said longitudinal axes lying in planes parallel to the plane of a diameter of said first gear passing through said particular point, a pair of terminals, means connecting each of said resistance elements to a different one of said terminals, whereby a rotation of the input shaft through a predetermined angle causes the brush to slide along said resistance elements thereby causing the resistance between the terminals to vary as the sine of said predetermined angle.

2. A device of the type described comprising an input shaft, an arm fixedly mounted to such shaft, a second shaft fixedly mounted to said arm outwardly of said input shaft and having an axis parallel to the axis of the input shaft whereby rotation of said input shaft will cause said second shaft to move in a circle about the axis of said input shaft, a stationary internal ring gear being so positioned that its axis is concentric to the axis of said input shaft, a second gear rotatably mounted on said second shaft and in driving connection with said internal ring gear, the gear ratio of said internal ring gear to said second gear being 2:1, a brush, means for mounting said brush to said second gear so that said brush overlies a particular point on the pitch circle of said second gear and the axis of said brush is parallel to the axis of said second shaft, a pair of rod-like linear resistance elements abutting said brush and in slidable engagement therewith, each of said resistance elements having a longitudinal axis, said longitudinal axes lying in planes parallel'to the plane of a diameter of said internal ring gear passing through said particular point, a pair of terminals, means connecting each of said resistance elements to a different one of said, terminals, whereby a rotation of the input shaft through an angle causes the brush to slide along said.

resistance elements thereby causing the resistance between the terminals to vary as the sine of the angle.

3. A device of the type described comprising an input shaft, an arm fixedly mounted to said shaft, an aperture in said arm outwardly of said input shaft, a second shaft fixedly mounted to said arm intermediate said input shaft and' said aperture and having an axis parallel to the axis of said input shaft whereby rotation of said input shaft will cause said second shaft to move in a circle about the axis of said input shaft, 'a third shaft rotatably received within said aperture, a first stationary gear being so positioned that its axis is concentric to the axis of said input shaft, a second gear rotatably mounted on said second shaft, a third and fourth gear respectively affixed to opposite ends of said third shaft whereby said third gear is in meaning engagement with said first gear and said fourth gear is in meshing engagement with said second gear, the gear ratio of said third gear to said fourth gear being 1:1, the gear ratio of said first gear to said second gear being 2:1, a fourth shaft, means for connecting said fourth shaft to said second gear and for positioning said fourth shaft so that it overlies a particular point on the pitch circle of said second gear and the axis of said fourth shaft lies in a plane parallel to the plane of the axis of said second shaft, a brush connected to the end of said fourth shaft and being positioned so that its axis is concentric with the axis of the fourth shaft, a pair of linear resistance elements abutting said brush and in slidable engagement therewith, each of said elements having a longitudinal axis, said longitudinal axes lying in planes parallel to the plane of a diameter of said first gear passing through the plane of said particular point, a pair of terminals, means connecting each of said resistance elements to a different one of said terminals, whereby a rotation of the input shaft through an angle causes the brush to slide along said resistance elements thereby causing the resistance between the terminals to vary as the sine of said angle.

4. In a device of the type described, an input shaft, an arm fixedly mounted to said shaft, a second shaft fixedly mounted to said arm outwardly of said first shaft and being positioned so that its axis is parallel to the axis of said input shaft whereby rotation of said input shaft will cause said second shaft to move in a circle about the axis of said input shaft, a. stationary internal ring gear being so positioned that its axisis concentric to the axis of said input shaft, a second gear rotatably mounted on said second shaft and in meshing engagement with said internal ring gear, said internal ring gear having twice as many teeth thereon as said second gear, a third shaft, means for connecting said third shaft to said second gear so that said third shaft overlies a particular point on the pitch circle of said second gear and the axis of said third shaft is parallel to the axis of said second shaft, a brush connected to the end of said third shaft with its axis concentric to the axis of said third shaft, said brush being composed of a conducting material, said shaft being composed of an insulating material, a'pair of linear resistance elements abutting said brush and in slidable engagement therewith, each of said elements having a longitudinal axis, said resistance elements being so positioned so that the longitudinal axes lie in planes parallel to the plane of a diameter of said internal ring gear passing through said particular point, a pair R=(A) sin where: R is the total resistance in ohms appearing between said terminals, A is the maximum amount of resistance appearing between said terminals in ohms, and 15 is the angle which the input shaft rotates through.

5. In a device of the type described, an input shaft, an arm fixedly mounted to said shaft, an aperture in said arm outwardly of said input shaft, a second shaft fixedly mounted to said arm intermediate said aperture and said input shaft and having an axis parallel to the axis of said input shaft, whereby rotation of said input shaft will cause said second shaft to move in a circle about the axis of said. input shaft, a first stationary gear rotatably mounted on said input shaft and being positioned so that its axis is concentric to the axis of said input shaft, a second gear rotatably mounted on said second shaft, said first gear having twice as many teeth thereon as said second gear, a third shaft rotatably received Within said aperture, a third gear fixedly mounted to said third shaft and in meshing engagement with said first gear, a fourth gear fixedly mounted to said third shaft and in meshing engagement with said second gear, said third and fourth gears having the same amount of teeth thereon, a fourth shaft connected to said second gear and so positioned that as to overlie a'particular point on the pitch circle of said second gear and having its axis parallel to the axis of said second shaft, a brush connected to the end of said fourth shaft and having an axis concentric to the axis of said fourth shaft, said brush being composed of a conducting material, said shaft being composed of an insulating material, a pair of rod-like linear resistance elements abutting said brush and in slidable engagement therewith, each of said elements having a longitudinal axis, said longitudinal axes lying in planes parallel to the plane of a diameter of said first gear passing through the projection of said particular point on said first gear, a pair of terminals, means connecting each of said resistance elements to a different one of said terminals, whereby the resistance appearing between said terminals varies according to the equation R=(A) sin where: R is the total value of resistance appearing between the termials in ohms, A is the maximum amount of resistance appearing between the terminals in ohms, and e is the angle that the input shaft rotates through.

References Cited by the Examiner UNITED STATES PATENTS 2,507,890 5/1950 Crowther 338-91 X ANTHONY BARTIS, Primary Examiner.

RICHARD M. WOOD, Examiner.

R. F. STAUBLY, Assistant Examiner. 

1. A DEVICE OF THE TYPE DESCRIBED COMPRISING AN INPUT SHAFT, AN ARM FIXEDLY MOUNTED TO SAID SHAFT, A SECOND SHAFT FIXEDLY MOUNTED TO SAID ARM OUTWARDLY OF SAID INPUT SHAFT AND HAVING AN AXIS PARALLEL TO THE AXIS OF THE INPUT SHAFT WHEREBY RELATION OF SAID INPUT SHAFT WILL CAUSE SAID SECOND ONE SHAFT TO MOVE IN A CIRCLE ABOUT THE AXIS OF SAID INPUT SHAFT, A FIRST STATIONARY GEAR BEING SO POSITIONED THAT IT AXIS IS CONCENTRIC TO THE AXIS OF SAID INPUT SHAFT, A SECOND GEAR ROTATABLY MOUNTED ON SAID SECOND SHAFT AND IN DRIVING CONNECTION WITH SAID FIRST GEAR, THE GEAR RATIO OF SAID FIRST GEAR TO SAID SECOND GEAR BEING 2:1, A BUSH, MEANS FOR MOUNTING SAID BUSH TO SAID SECOND GEAR AND FOR POSITIONING SAID BUSH SO THAT IT OVERLIES A PARTICULAR POINT ON THE PITCH CIRCLE OF SAID SECOND GEAR AND THE AXIS OF SAID BRUSH IS PARALLEL TO THE AXIS OF SAID SECOND SHAFT, A PAIR OF LINEAR RESISTANCE ELEMENTS ABUTTING SAID BUSHING AND IN SLIDABLE ENGAGEMENT THEREWITH, EACH OF SAID RESISTANCE ELEMENTS HAVING A LONGITUDINAL AXIS, SAID LONGITUDINAL AXES LYING IN PLANES PARALLEL TO THE PLANE OF A DIAMETER OF SAID FIRST GEAR PASSING THROUGH SAID PARTICULAR POINT, A PAIR OF TERMINALS, MEANS CONNECTING EACH OF SAID RESISTANCE ELEMENTS TO A DIFFERENT ONE OF SAID TERMINALS, WHEREBY A ROTATION OF THE INPUT SHAFT THROUGH A PREDETERMINED ANGLE CAUSES THE BRUSH TO SLIDE ALONG SAID RESISTANCE ELEMENTS THEREBY CAUSING THE RESISTANCE BETWEEN THE TERMINALS TO VARY AS THE SINE OF SAID PREDETERMINED ANGLE. 